Assessing risks from operator fatigue

8/9/2019 Assessing risks from operator fatigue

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Guidance document for the oil and gas industry

Assessing risks from

operator fatigue

Health

2014


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E-mail: [email protected] Internet: www.ogp.org.uk

OGP Report Number 492

This publication has been developed to support the implementation of IPIECA’s and OGP’s

mission and vision. Whilst every effort has been made to ensure the accuracy of the information,

it is intended to provide general guidance only. It is not designed to provide legal or other advice,

nor should it be relied upon as a substitute for appropriate technical expertise or professionaladvice. All attempts have been made to ensure the information is correct at of the date of

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Assessing risks fromoperator fatigue

Guidance document for the oil and gas industry

Photographs reproduced courtesy of the following: cover (upper left and right): ©iStockphoto.com;(upper centre and bottom): ©Shutterstock.com; pages 3, 14, 15 and 20: ©Shutterstock.com; page 21:©iStockphoto.com

Acknowledgements

This document was prepared by the Fatigue Risk Assessment Task Force onbehalf of the Health Committee. The Health Committee gratefullyacknowledges the work of Ron McLeod (of Ron McLeod Ltd) in preparingthis document, and would also like to thank Adam Fletcher (IntegratedSafety Support), Alexandra Holmes and Paul Jackson (Clockwork Research)

and Kirsty McCulloch (The Keil Centre) for reviewing the document.


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OGP • IPIECA

ii

ASSESSING RISKS FROM OPERATOR FATIGUE

Contents

Executive summary 1

Introduction 2

Definition 3

Structure of the document 3

Approaches to fatigue risk assessment 4

Defences and tolerability 4

A process for performing 5

a fatigue risk assessment

Stage 1: Screening 6

Step 1: Define the assessment unit(s) 6

Step 2: Assess activity fatigue sensitivity 7

Step 3: Potential consequences of fatigue impairment 9

Output from Stage 1 10

Stage 2: Detailed analysis 10

Step 4: Define action levels 11

Step 5: Estimate the fatigue exposure 11

Step 6: Define action plan 19

Quality assurance 21

Competence to perform a fatigue risk assessment 22

References 23

Appendix A: Estimating potential task 24

sensitivity to fatigue impairment

Example 1: Fork lift truck operator 24

Example 2: Field operator tasked with closing 24

a manually operated valve

Example 3: Control room operator—modern, 24

highly automated system with large control team

Example 4: Control room operator—one-man 25

control room with less automated system

Step 1: Estimating the activity fatigue sensitivity 25

Step 2: Fatigue barrier factor 27

Step 3: Fatigue task sensitivity 28

Appendix B: The Prior Sleep Calculator 29

Appendix C: Recommended fatigue 31data recording


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This document provides guidance on assessing

risks from operator fatigue in the oil and gas

industry. Designed to support operating

companies, contractors and service companies,

it complements two existing OGP-IPIECA

publications on fatigue risk management:

Managing fatigue in the workplace: A guide for oil

and gas industry supervisors and occupational health

practitioners (2007) and Performance indicators for

fatigue risk management systems: Guidance

document for the oil and gas industry (2012).

Assessing risks from operator fatigue: Guidance

document for the oil and gas industry describes a

structured approach to implementing a fatigue

risk assessment (FRA). Recognizing that the

impacts of fatigue vary in different situations,

this document provides guidance on factors for

determining the applicability and acceptability

of assessed levels of fatigue. The guide offers a

standardized method (with suggested support

tools) for documenting and reporting anassessed level of fatigue risk. The approach

described could potentially support cross-

industry benchmarking.

The Introduction describes the scope and

structure of the document, and defines fatigue

and fatigue risk assessment.

The following section on Approaches to fatigue

risk assessment identifies three recognizably

different situations when an FRA may be

required, and discusses the importance of

barriers when deciding what level of fatigue

might be considered tolerable.

The third section, entitled A process for

performing a fatigue risk assessment, describes a

two-stage approach to preparing for,

implementing and interpreting an FRA. Stage 1is an initial screening, which will help to

determine whether a detailed risk assessment,

Stage 2, is required.

The section on Quality assurance makes

recommendations to help deliver consistency

and quality in fatigue risk assessments and

reporting.

Three Appendices are included. Appendix A

provides a model process for assessing whetheractivities are likely to be at risk from fatigue.

Appendix B offers a version of a public-domain

tool, the ‘Prior Sleep Calculator’. Modified to

better suit oil and gas operations, this tool can

be used to support decisions to define, at any

time, an individual’s likely fatigue level and to

determine whether action may be needed to

reduce the risks associated with that individual’s

work. Appendix C contains suggestions for data

reporting of fatigue risk assessments.

1


Executive summary


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This document provides guidance to operating

companies, contractors and service companies

on assessing risks from operator1 fatigue in the

oil and gas industry2.

The document complements two other

OGP/IPIECA publications on the topic of fatigue

risk management:l Managing fatigue in the workplace: A guide for

oil and gas industry supervisors and

occupational health practitioners (OGP report

number 392, 2007) explains the health and

safety risks posed by fatigue, provides

background information on sleep and the

body clock, describes the main causes of

fatigue and provides strategies for managing

the causes.

l Performance indicators for fatigue risk

management systems: Guidance document for

the oil and gas industry (OGP report number

488, 2012), proposes indicators that can be

used to monitor the effectiveness of a fatigue

risk management system (FRMS).

The ‘Performance indicators’ report states that,‘While data-driven decision making is clearly a

desirable aspiration, the reality for many companies

is that hard data on fatigue are difficult to come by.

In most cases, where data are not available,

decisions are risk based. An FRMS therefore needs

to be properly grounded in assessment of the risks

facing the operation or organization’. The report

also indicates that the existence an FRA can in

itself be a leading indicator of controls against

OGP • IPIECA

2

Introduction

1 Throughout the document, the term ‘operator’ refers to ‘employees’ as opposed to ‘operating company’.2 The scope and level of detail contained in this document is based on the recommendations from a workshop organized by

IPIECA and held in Rio de Janeiro in November 2013.


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fatigue. It also proposes measures that can be

used to assess the effectiveness of a fatigue risk

assessment programme.

This document supports the two reports

mentioned above in the following four ways:l It sets out and illustrates a structured

approach to performing a fatigue risk

assessment.l It provides guidance on considerations that

should be taken into account in determiningwhether the assessed level of fatigue can be

considered acceptable in different situations.l It proposes a standardized method of

documenting and reporting an assessed level

of fatigue risk that could potentially be used

to support cross-industry benchmarking.l It provides some suggested tools that can be

used to support the proposed approach.

Definition

Fatigue (mental fatigue) is a progressive decline

in alertness and performance caused by

insufficient quality or quantity of sleep,

excessive wakefulness, or the body’s daily

circadian rhythm.

A fatigue risk assessment is a structured,

evidence-based assessment of the likelihood

that fatigue could reduce the ability of anindividual who is otherwise fit to work to

maintain the levels of attention and cognitive

performance necessary to perform an assigned

activity to the expected standard during a

defined period of time.

3



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The approach to performing a fatigue risk

assessment will depend on why the assessment

is being performed, and on the scope and

complexity of the operations involved. An

assessment may be needed to assess the risk of

an individual working extended overtime on a

particular day. Alternatively, it could be required

to assess the risk of operator fatigue in terms of

the potential for major accidents at an entire

worksite or asset. The situations in these two

examples are very different, and although similarfactors will need to be taken into account,

different approaches to the assessment, involving

different levels of detail, will be required for each

case. An FRA may be performed by individuals with

different backgrounds, experience and knowledge.

In the first example, the assessment may be carried

out by a local supervisor or a operations manager

having considerable operational experience but

little in-depth knowledge of the science behind

human fatigue. The second example is likely to

require a fatigue specialist (see Competence to perform a fatigue risk assessment on page 22).

In general, there are three identifiable situations

that will require different approaches to

conducting a fatigue risk assessment.

1. Individual: Assessing the risk that a particular

individual may become unfit to work safely

over a specific period of time due to fatigue.

2. Job or activity: Assessing the risks of fatigue

associated with a specific activity or operation

being carried out by a defined group of peopleunder the same work arrangements. For

example assessing the risk of fatigue associated

with a specific job, or planning for an unusually

complex or hazardous activity to be performed

by a team over a few days or weeks.

3. Population: Assessing the fatigue risk that

could exist at a whole site covering a range of

activities and a diverse workforce.

Defences and tolerability

Assessing whether a given level of fatigue can be

considered tolerable requires consideration of

other barriers or defences that may be expected

to intervene if an operator’s performance is

impaired by fatigue. A higher fatigue exposure

may be considered tolerable if there are

adequate additional defences in place.

For example, if a driver who is alone in a carexperiences a microsleep there are limited

barriers or defences that will intervene to

prevent an accident. By contrast, if a control

room operator or field operator falls asleep, or if

the operator’s level of attention is reduced due

to fatigue, a number of defences should be

available—from alarms to the presence of other

people as well as automatic shut-down

systems—that may reduce the potential for a

serious outcome. An organization may therefore

decide to tolerate a higher level of fatigue incontrol room or field operators than they would

for a lone driver.

It should be noted, however, that this argument

should not be applied if the operator’s tasks are

explicitly relied on as process safety barriers3.

OGP • IPIECA

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Approaches to fatigue risk assessment

3 Process safety barriers are measures or controls that an organization relies on to mitigate the risk of events occurring

involving loss of containment of hydrocarbons or other highly hazardous materials, or of such a loss escalating and leading to

significant loss of life, or damage to assets or reputation. Process safety barriers can be mechanical, electrical, human or

organizational in nature.


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A fatigue risk assessment can be performed

efficiently in two stages4, as described below.

Stage 1: a high-level screening comprising the

following three objectives:

1. Define the target workforce and the scope

and timescale of operations to be assessed

(i.e. the ‘assessment unit(s)’).

2. Identify whether any of the critical operator

activities within each assessment unit are

likely to be sensitive to impairment by fatigue.3. Identify the potential consequences of fatigue

leading to significantly impaired performance

in any of the activities.

Stage 1 leads to a decision on whether a

detailed FRA is needed (Stage 2).

Stage 2: A detailed risk assessment comprising a

further three objectives:

4. Define the maximum level of fatigue

exposure that would be considered tolerablefor the critical activities performed by the

assessment units.

5. Estimate the expected level of fatigue exposure.

6. If the anticipated level of fatigue is greater

than the level considered tolerable, determine

what action can be taken to reduce the

fatigue exposure, or what additional controls

should be implemented to reduce the risk to

an acceptable level.

The two stages are summarized in Figure 1 andexplained below.

Most organizations should be able to complete

Stage 1 using the guidance provided in this

document, drawing on appropriate operational

and safety management experience. For

relatively simple situations, a competent health

or safety professional should be able to perform

5


A process for performing fatigue risk assessments

4 For clarity and simplicity these two stages are set out sequentially. However, where a fatigue risk assessment forms part of a

broader human reliability assessment, or if it is led by a specialist in human reliability analysis, the two stages could be

conducted in either order.

S

T A G E 1 : S c r e e n i n g

S T A G E 2 : D e t a

i l e d F R A

Step 1:Define assessment units (AUs)

Step 2:Review fatigue sensitivity

Step 3:Assess potential consequences

Is a detailed FRA needed?

l Assessment unit(s)

l List of critical activities per AU

List of fatigue sensitivities

Scope of detailed FRA

OR

NO

Complete

OR Complete

Complete

YES

Step 4:Define action levels

Step 5:Estimate fatigue exposure

Step 6:Assess tolerability

Fatigue action levels

Estimated or measured fatigue exposure

FRA report and action plan

Complete

Figure 1 Recommended process for performing a fatigue risk assessment

the more detailed analysis involved in Stage 2,

again using the guidance in this document.

More complex situations will require greatercompetence in fatigue risk management.

The six steps involved in Stages 1 and 2 can be

completed in different ways dependent on the

scope of the assessment, the skill and experience

of the assessors, the nature of the tasks and

operations being assessed, and the regulatory

and legal context of the assessment.


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Furthermore, the scientific knowledge base

underpinning understanding and prediction of

risks from fatigue is developing rapidly.

For these reasons, this section only describes

and illustrates the six steps. It does not try to

define precisely how each step should be

completed; that is left to the discretion and

judgment of the organization responsible for the

assessment, suitably informed by this guidance,

and by competent people. The appendices onpages 24–32 provide examples of tools that may

be useful in completing some of the steps.

Stage 1: Screening

The purpose of the screening stage is to clarify

the scope of the assessment and to decide

whether there is a need to perform a more

detailed analysis. The screening considers the

nature of the operations involved, the potential

consequences if workers become impaired by

fatigue, and the existence of other defences that

may be relied on to mitigate the effects of

fatigue. Appendix A contains a procedure that

may be helpful in completing Stage 1.

Stage 1 may not be necessary if the scope of the

assessment is clear, or if the organization

believes that the people involved in the activities

are at risk from fatigue, and that the

consequences of fatigue could be significant.However, Stage 1 should be completed if the

organization believes, with no reasonable

evidence, either that critical activities will not be

at risk from fatigue, or that any fatigue-induced

impairment would corrected by other defences

Figure 2 summarizes Stage 1, showing the

decisions and outputs from each of the three

steps. Note that the figure shows that it is

possible for the process to finish at the end of

steps 2 or 3, depending on the results andconclusions from those steps.

Stage 1 therefore provides clarity on the potential

risk from fatigue that may exist in each assessment

unit, and leads to a decision on whether or not a

more detailed analysis is required. If a more

detailed analysis is considered necessary, Stage 1

should define the scope of that analysis.

Step 1: Define the assessment unit(s)

The first step is to set the boundaries of the FRA

by defining the people or roles to be assessed,

and the activities and timescale to be covered.

In common with the guidance for performing

health risk assessments (OGP-IPIECA, 2006),

these are referred to as ‘assessment units’.

The basis for grouping roles and operations into

assessment units is a matter of judgment, taking

account of factors such as:

l the nature of the operations, processes andtechnologies involved;

l inherent risks;

OGP • IPIECA

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Figure 2 Summary of Stage 1 (Steps 1, 2 and 3 of the overall FRA process)


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l work schedules (in terms of daily hours of

work in a shift) and rotations (sequences of

consecutive work shifts over a period of time);l working and living arrangements of the

workforce (i.e. workers living at home and

travelling to work each day may need to be

treated differently from those who live in

camp or at the asset while on a rotation); andl geographical location.

At a simple level, the assessment unit could be aparticular individual doing a few hours overtime

to finish a critical job. The assessment unit in this

case would be the named individual, doing the

specified work, over the defined time.

Alternatively, the assessment unit could be a

small group of people doing a limited range of

activities, e.g. driving, monitoring computer

displays or doing equipment rounds, over a

period of a few weeks when there is expected to

be higher than usual workload.

On a larger scale, an assessment unit could include

everyone working on, or supporting, an entire

worksite or facility over an entire year. In this

case the population may need to be organized

into a number of discrete assessment units.

For each assessment unit, a summary of the

activities that are considered most critical for the

purpose of the analysis should be prepared. The

degree of ‘criticality’ in this sense will depend onthe purpose of the analysis: this may be process

safety, personal safety, environmental control,

security, production, reputation or even

competitive position in a market5.

Being clear about the timescale of the

operations to be covered is especially important

in defining the assessment unit(s). The issues to

be taken into account in assessing the inherent

fatigue risk over the course of a year can be very

different from assessing the risk of someone

continuing to work for a few hours. There may

also be regional or geographical differences: in

operations at high latitudes for example, where

there is very little daylight during the winter

months, and very little darkness in summer,

there can be significant variations over the year

in the extent to which the circadian rhythms of

shift workers are able to adapt to working at

night, with consequences for sleep and fatigue.

Step 2: Assess activity fatigue sensitivity

The purpose of Step 2 is to determine whether

any of the critical operator activities within

each assessment unit are likely to be sensitive

to significant impairment by fatigue. This will

be referred to throughout this document as the

‘activity fatigue sensitivity’. At this stage it is

only necessary to make a high-level judgement:

if it is concluded that none of the activities are

likely to be sensitive to fatigue, it may not benecessary to take the analysis further.

This decision needs to consider both potential

impairment to specific tasks, as well as a

generally reduced capability to work,

independent of specific tasks.

Task-independent fatigue sensitivity

Many of the effects of fatigue are the

consequence of the negative impact of fatigue

on an individual’s level of energy and/ormotivation: this may include a reduction in an

individual’s ability to pay attention, to attend to

detail, to check, question or find out if there is

uncertainty, to notice or react to information.

This general decline in energy can have an

impact on nearly every human activity.

Potentially, there is a risk that a seriously

fatigued person will perform all activities less

well than an alert and motivated individual.

7


5 A fatigue risk assessment cannot meaningfully be applied at the level of a whole business, unless the business only has a single

type of operation that is organized in exactly the same way within a limited geographical region.


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Task-specific fatigue sensitivity

Some types of cognitive and psychomotor tasks

are particularly sensitive to impairment from

fatigue. The general characteristics of these tasks

are summarized in Box 1.

To take driving as an example, task-specific

fatigue sensitive activities would include the

cognitive demands associated with:l continuous attention and concentration over

an extended period to control the vehicle’s

speed and position on the road;l detecting and responding to variations in the

road conditions; andl predicting, detecting and responding to the

behaviour of other road users.

Professional drivers also perform many other

activities, including journey planning, checking

loads, securing the vehicle, refuelling, etc.

However, most of these will be less prone to

impairment by fatigue than the core driving task.

The critical activities within the scope of each

assessment unit should be reviewed to decide

whether any of them are likely to rely on any of

the characteristics shown in Table 1, or whether

there may be other reasons for concern with

regard to their potential impairment by fatigue. In

some situations6, this could require a task analysis

to be performed. In many cases, however, it will

be clear from an understanding of the operation

whether there is likely to be a high reliance on

fatigue-sensitive task characteristics: driving a

car or a crane, monitoring computer displays in a

control room or overseeing operations on a drill

floor all clearly rely on the ability to monitor or

pay attention to information and events over a

sustained period of time.

Appendix A includes a possible approach to

estimating the activity fatigue sensitivity of

different types of activities.

Step 2 therefore involves reviewing each

assessment unit, and considering the following

three issues:l Do any of the critical activities rely on

characteristics known to be particularly

sensitive to fatigue?l Even if none of the tasks involved are

specifically sensitive to fatigue, could there

still be significant risk from errors due to

reduced motivation as a result of fatigue?

OGP • IPIECA

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Box 1 Examples of task characteristics that can be especially sensitive to fatigue

l Monitoring or paying attention to information or events over a sustained period of time

l Reasoning, performing mental calculations, making sensitive judgements or decisions involving complexinformation, especially where there is uncertainty

l Attending to, or using, detailed information or procedures especially where there is a high reliance onmemory or knowledge

l Detecting, acknowledging and/or correctly interpreting alarms, especially when there are multiple similaralarms and understanding the meaning relies on correctly interpreting details (e.g. tag numbers), or wherethere is a high alarm rate with many false or nuisance alarms

l

Being aware of changes in the operational situation or risk exposurel Assessing or prioritizing risk in a complex multi-risk environment

l Communicating or understanding detailed information in communications

6 For example complex and infrequently performed start-up/shutdown activities, extensive maintenance on pressurized or H2S

systems, or simultaneous operations (SIMOPS).


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l If the answer to both of these questions is ‘no’,

then there will be little justification for

continuing the analysis for that unit.

Step 3 should be followed for each assessment

unit where the answer to either question is ‘yes’.

Step 3: Potential consequences of fatigue

impairment

The third objective of Stage 1 is to identify thepotential consequences that may result if fatigue

leads to significantly impaired performance of

any of the critical activities.

Exposure to fatigue in itself, or impaired task

performance due to fatigue, is not necessarily a

risk. The potential consequence of any given

fatigue level depends on a number of

considerations, including:l the hazards associated with the operation

(such as the presence of hydrocarbons, highpressure, or sources of energy);

l the activity fatigue sensitivity of the activities

involved (i.e. the potential that an activity

may not be performed to the expected

standard as a consequence of fatigue); andl the existence of other barriers or defences

that could either prevent fatigue leading to

task impairment or prevent a fatigue-induced

mistake or omission from contributing to an

incident.

It is assumed that the organization undertaking

the risk assessment will understand the hazards

associated with the target workforce and

operations. Usually, hazards are assessed using

some form of risk assessment matrix (RAM)

(Dawson et al., 2011) that provides a

standardized rating of the relative risks

associated with an operation. Organizations

should use whichever RAM process they are

familiar with to assess the potential

consequence of fatigue-impaired performance.The potential activity fatigue sensitivity should

have been assessed in Step 2.

Step 3 involves judging whether, in the event of

fatigue impairing the performance of a critical

activity, other barriers or defences could be

expected to be relied on to intervene and

prevent the undesired consequences (see Box 2).

Appendix A provides a possible means of

assessing the likely strength of other barriers to

prevent fatigue impairment from contributing to

an incident (termed the ‘fatigue barrier factor’).

To make this judgement with any confidence, anorganization will need to be able to draw on a

deep knowledge of local operational procedures

and practices.

9


Box 2 Assessing the likelihood that interventions may

be relied upon to prevent undesirable consequences

Knowing whether or not barriers or defences

exist which could be expected to intervene toprevent undesirable consequences requires athorough knowledge of the specific operationalprocedures. For example:

l If a control room operator falls asleep at aconsole, how likely is it that neither theoperator nor anyone else would detect a highlevel alarm on the console?

l If a field operator who is seriously fatiguedmishears a radio instruction and, as a result,attempts to perform an action on the wrongpiece of equipment, how likely is it that the

error would be noticed and an interventionmade before the action was taken?

In both of these examples, the answer willdepend on many factors. In the case of thealarm, other defences might include thepresence of other people in the control room,whether there is an audible as well as a visualalarm, the location of the alarm panel relative tothe operator, and the level of backgroundacoustic noise. For the field operator, the answermay depend on whether they are working alone,and what procedures are in force at the site for

confirming actions on equipment before andafter they are taken.


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Output from Stage 1

The output from the screening conducted in

Stage 1 is a decision about whether there is a

need to proceed to Stage 2 and carry out a

detailed FRA.

Appendix A provides a possible means of

combining the likely activity fatigue sensitivity

with the fatigue barrier factor to assess the likely

level of risk that may be associated with fatigue

for the critical tasks involved in the assessment

unit.

If there is a case for a detailed FRA, Stage 1

should define the scope of the analysis in terms

of at least the following:l The assessment units to be covered (operations,

operator roles and geographical location).l The work schedules, rotations and living

arrangements of the workforce involved.l The timescale and duration of the activities to

be covered by the assessment.

Stage 2: Detailed analysis

The second stage of the recommended

approach addresses the remaining three steps in

the fatigue risk assessment process:

Step 4: Define the maximum level of fatigue

exposure that would be considered

tolerable for the critical activities

performed at the assessment unit(s).

Step 5: Estimate the expected fatigue exposure.

Step 6: If the anticipated level of fatigueexposure is greater than the level

considered tolerable, determine what

action can be taken to reduce the

fatigue exposure, or what additional

controls should be implemented to

reduce the risk to an acceptable level.

Stage 2 should only be applied to those

assessment units and critical activities identified

in Stage 1 as justifying a detailed FRA. Figure 3

summarizes Stage 2, showing the decisions andoutputs from each of the three steps.

OGP • IPIECA

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Figure 3 Summary of Stage 2 (Steps 4, 5 and 6 of the overall FRA process)


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Step 4: Define action levels

The purpose of Step 4 is to determine what level

of fatigue can be considered tolerable for the

target workforce performing the activities of

interest. This can be among the most difficult

decisions to make, although it is probably the

most important.

There are currently no regulations or other

standards that define a level of fatigue that

would be acceptable for any operation: existing

regulations and standards generally focus on

work and rest time, and some require

implementation of fatigue risk management

systems in certain situations. While these require

compliance, and can limit exposure to fatigue

risk, none define the level of fatigue considered

tolerable for any activity. Each organization must

therefore make its own judgement about the

level of fatigue risk that it considers tolerable. As

far as possible, such judgements should be

evidence based, and consistent both withscientific knowledge and industry good practice.

The following considerations should be taken

into account when attempting to determine a

tolerable level of fatigue:l It should be set in advance of the assessment

of fatigue exposure. Determining tolerance

levels after fatigue exposure in a workforce

has been estimated has the potential to be

unduly influenced, or biased, by operational

considerations.l The tolerance level should, as far as possible,

be based on an objective and evidence-based

assessment of the potential consequences of

a fatigued individual not being able to

perform the activity to the standard expected.l A tolerance level is a maximum level that can

be considered acceptable for an activity

without additional controls being in place. It

does not mean that an individual

experiencing the estimated level of fatigue

cannot perform the work safely; but it doesmean that if the tolerance level is exceeded,

additional controls need to be put in place to

ensure that the operation is not exposed to

an unacceptable level of risk.l Tolerance levels need to reflect the inherent

fatigue sensitivity of the activities being

assessed (i.e. the combination of the likelihood

that fatigue may impair performance of an

activity, and the potential consequence if

performance is actually impaired by fatigue). If

activities within the scope of an assessment are

considered to have different inherent fatiguesensitivities, it may be therefore necessary to

adopt different tolerance thresholds.l Tolerance levels must recognize individual

differences in the way people may be affected

by a given fatigue level, i.e. they should

recognize variability between individuals as

well as variability in the same individuals over

time. It may not be operationally realistic to

base a tolerance level on the worst case (i.e.

individuals whose performance may be

significantly impaired at relatively low fatigueexposures). It would, however, be risky to

adopt a tolerance level that reflects the

expected impairment of the population

average: this could mean accepting a level of

risk while anticipating that up to 50% of the

activities may be exposed to a greater level of

impairment than is considered to be tolerable.

The way tolerance limits are expressed needs to

be consistent with the way fatigue exposure is

estimated. If, for example, an assessment of likelyfatigue exposure is made using a

biomathematical model, the tolerance

thresholds should similarly be expressed in the

scores produced by the model.

Step 5: Estimate the fatigue exposure

Risk assessment is about predicting the level of

risk that is likely to be experienced in a

population at some time in the future. There are

two general approaches to predicting the levelof fatigue that individuals or a population are, or

are likely to be, exposed to. These are:

11



16/40

l measuring the level of fatigue that currently

exists in an equivalent population, and

extrapolating forward to the future

population in similar circumstances; andl predicting the level of fatigue that is likely to

be experienced based on knowledge of the

factors and mechanisms that cause fatigue,

the relevant characteristics of the target

population and estimates of their expected

exposure to those causal factors.

Fatigue continues to be the topic of a significant

body of high quality scientific research, both

applied and theoretical. Research is continually

revealing better ways of both measuring and

predicting fatigue.

Measuring fatigue

Approaches to measuring fatigue range from

subjective measures, usually using a validated

rating scale (such as the Karolinska Sleepiness

Scale) through more objective performance-based measures (such as the Psychomotor

Vigilance Task), to electrical and chemical

measures of brain activity and biomarkers taken

from urine or blood samples. However, currently

there is insufficient evidence for the rigour of

biomarker use in operational environments.

Technologies are also available that are designed

to be worn or attached to the body while people

continue to work. Examples include actigraphy7

which can give an indication of the amount of sleep obtained over a period of time, as well as a

range of devices developed to monitor an

individual’s state of alertness and detect

drowsiness, most commonly among drivers.

Measurement of mental fatigue and sleep can

provide a good basis for estimating the level of

fatigue likely to be experienced in the future

(assuming, of course, that no significant change

occurs in the meantime). However, gathering the

data, interpreting it and extrapolating to the

future are specialist activities. Where technically

and logistically practical, measures of actual

fatigue should be used as the basis for

predicting future fatigue. Undertaking these

measures is beyond the scope of this

recommended practice. Organizations wishing

to base an assessment of future fatigue risks on

measures of actual fatigue, should use specialists

with the skills, knowledge and experience tomake valid measurements, and who know how

to interpret and extrapolate them.

Predicting fatigue

The science base has generated a good

understanding of the causes, mechanisms and

effects of fatigue on human performance. Based

on that understanding, a variety of

biomathematical models are now available that

can predict the levels of fatigue likely to be

experienced based on factors such as anindividuals recent sleep history and the time of

day8. Table 1 (page 13) summarizes some of the

more widely used models for predicting fatigue

or estimating an individual’s likely state of

alertness. In each case, the table gives examples

of what the developers of the models claim the

scores produced mean. Some regulators

(ITSR, 2010) have published comments and

expressed views on the interpretation of the

fatigue scores produced by some of these

biomathematical models.

The scores shown in Table 1 should not, on their

own, be treated as thresholds. As discussed in

Step 4, deciding what level of fatigue might be

considered tolerable depends on many factors,

not least the inherent activity fatigue sensitivity,

and, as mentioned in Step 3, what barriers are in

place to manage the risks of fatigue-impaired

task performance.

OGP • IPIECA

12

7 Actigraphs are devices worn on the wrist, which passively collect activity data and use this to give an indication of sleepobtained over a period of time.

8 See Dawson et al. (2011) for a review of biomathematical approaches to modelling fatigue.


17/40

Biomathematical models that predict the level of

fatigue likely to be experienced in a population

should, as a minimum, take into account:

l the amount and quality of sleep thatindividuals working in an operation are likely

to get in each 24-hour period;l how long they are likely to have been awake

at the time of work; andl the effect the body’s circadian rhythm is likely

to have on alertness levels at the time work is

performed.

Some models also take into account variables

such as the characteristics and demands of the

work being performed, opportunities for restwhile awake, as well as the value of short sleep

periods (‘naps’) during the working day. The

most sophisticated models claim the capability

to make allowance for factors such as circadian

adaptation (the way in which the timing of an

individual’s daily sleep cycle adapts to a changein time zone, or a change in the timing of sleep,

for example when working night shift), as well as

individual differences.

The ability to measure or estimate the parameters

required by any biomathematical model depends

on how specific the assessment is to a particular

population and work situation. The more specific

the assessment is in terms of the individuals

involved, the timing of the work, travel and other

issues that can impact on the obtained sleep andthe time since the last sleep, the more accurate

will be the assessed exposure to risk from fatigue.

13


Table 1 Examples of fatigue models, predicted fatigue output scores and their interpretation

Model InterpretationScores

Prior Sleep Calculator(PSC)

UK HSE Fatigue andRisk Index(HSE, 2006)

FAID® (FatigueAssessment Tool byInterDynamics)(FAID®, 2014)

FAST (FatigueAvoidanceScheduling Tool)(FAST, 2014)

PSC Score

Fatigue Index(FI)

Risk Index(RI)

FAID Score

Effectiveness

Score ranges from 1 to more than 11. See Appendix B for details.

An FI of 20.1 equates to the levels of fatigue experienced by an individual working a two-day, two-night, four-off schedule, involving 12-hour shifts starting at 08:00 and 20:00(DDNNRRRR9 — i.e. 2 day shifts, followed by 2 night shifts, followed by 4 rest days).

An RI of 1 reflects the relative likelihood of an incident or accident for an individualworking a two-day, two-night, four-off schedule, involving 12-hour shifts starting at 08:00

and 20:00 (DDNNRRRR).A FAID score of 40 is equivalent to the maximum fatigue, which would be experiencedduring a 09:00 to 17:00, Monday to Friday workweek.

A FAID score of 80 is approximately 200% of the maximum fatigue that would beexperienced during a 09:00 to 17:00, Monday to Friday workweek. A score of 80 has beenfound to be similar to 21–22 hours of continuous sleep deprivation (when the sleepdeprivation begins at 08:00).

FAID scores of 80 have been equated to an equivalent level of performance impairmentin some psychomotor tasks as has been observed in laboratory subjects with a bloodalcohol concentration (BAC) of 0.05% for 17 hours of continuous sleep deprivation (whenthe sleep deprivation begins at 08:00). A score of 100 has been equated to a BAC of 0.08%, which has been found to be similar to 21–22 hours of continuous sleep

deprivation.

Risk of human factors accidents elevated at effectiveness scores below 90 and increasesprogressively with reduced effectiveness.

Human factors accidents when average effectiveness is less than 77 is considered 2½times more costly than similar accidents when effectiveness is greater than 90.

9 D = day N = night R = rest day


18/40

An especially important limitation of

biomathematical models is that they only

produce population averages, i.e. they represent

a ‘typical’ or ‘average’ person. Currently, no

models are available commercially, nor are there

any under development, that are capable of

predicting the fatigue that a specific individual

in a specific situation will experience. This can be

a significant limitation; while some people will

experience less fatigue than is predicted, others

will experience more.

This limitation of biomathematical models has

been recognized, and is a concern to regulators.

For example, in 2010, building on work of the US

Department of Transportation Federal Railroad

Administration, Australia’s Transport Safety

Regulator published a Transport Safety Alert

concerning the use of biomathematical models

of fatigue (ITSR, 2010). Among other

recommendations, this stated that:

“… models that are based on group average data

should not be used as the sole basis for decisions

on fatigue impacts on individual workers.

Individual factors and the risk context should also

be examined in each case”. It concluded that:

“When setting criteria for safety risk decision

making, rail transport operators should take into

consideration the risk context and the basis of any

recommended limits that may be associated with

particular models.”

However, if biomathematical models are used

appropriately, and if the results are interpreted

intelligently, taking account of the assumptions

and limitations associated with each, they can

provide an effective means of estimating the

typical fatigue likely to be experienced in

operational settings.

Biomathematical models can be used, where

appropriate, to support fatigue risk assessments

for oil and gas operations. However, they mustbe used with caution, recognizing the

assumptions and limitations inherent to each

model, and there must be recognition that the

maximum fatigue exposure in the workforce

being assessed may be significantly higher than

that predicted by any model.

It is important to note that currently available

models vary greatly in their degree of

sophistication, their scientific validity, and their

suitability for use by non-professionals. In mostcases, the mathematical algorithms they are

based on continue to be the subject of ongoing

research and validation. None of them are

perfect, and none are capable of being applied

‘off-the-shelf’ to the full range of situations

experienced in the global oil and gas industry.

None of them have been validated for fly-in fly-

out operations that are common in the oil and

gas industry. They all need to be used with

caution.

This document does not recommend any one

particular biomathematical model. That decision

OGP • IPIECA

14


19/40

is left to organizations wishing to adopt a

model-based approach.

The Prior Sleep Calculator

The Prior Sleep Calculator (PSC) is a simple

means of estimating an individual’s likely state of

alertness either at a given time or in the near

future (assuming they remain awake)10. It can be

used to support a situational fatigue risk

assessment, for example if a situation arises

where there is a need for someone who isalready at work to continue to work for a few

hours beyond his or her rostered hours.

The calculator is based on scientific research

that has demonstrated a strong relationship

between three factors: how long an individual

has been awake, how much sleep they have had

in the previous 24 and 48 hours, and their ability

to remain alert and to think clearly and quickly.

The PSC uses the actual sleep obtained by the

individual in the previous 24 and 48 hours, aswell as the actual length of time they have been

awake. Based on these three parameters, it

indicates the individual’s likely state of alertness

at the time. By allowing for additional waking

hours beyond the current time, it is also able to

suggest an individual’s likely state of alertness in

the near future.

Appendix B presents a variant of the Prior Sleep

Calculator that may be appropriate for

application in the oil and gas industry. (Theversion contained in Appendix B differs from

other versions available in the public domain in

the meaning and recommendations that are

associated with each level of the scale).

The calculator can help in deciding whether

someone is likely to be able to work safely now

or at some time in the coming hours. The

estimates are useful for most people, most of the

time, but the recommendations must be treated

with caution; the calculator is not an exactscience and the calculated scores can be no

more than a guide to the likelihood of a ‘typical’

individual being in a fatigued state.

Organizations considering using the PSC should

take care to ensure that it is used appropriately

and for specific situations, and that the advice

and recommendations that it provides are

consistent with the organization’s experience

and are appropriate for the activities involved.

Using the calculator does not remove anorganization’s responsibilities to comply with the

law, their own company’s health and safety

management systems, or other relevant

requirements for the safe management of work,

including workforce agreements.

Table 2 illustrates how different approaches

might be needed in conducting a fatigue risk

assessment in a number of different situations.

15


10 Note: the PSC can be readily implemented as a simple ‘app’ or online tool in which the user simply enters the data and the tool

provides a recommendation.


20/40

OGP • IPIECA

16

T a b l e 2

T h e d i f f e r e n t a p p r o a c h e s t o p e r f o r m i n g f a t i g u e r i s k a s s e s s m e n t s i n d i f f e r e n t s i t u a t i o n s

P o p u l a t i o n

t o b e

a s s e s s e d

T i m e

p e r i o d

N o . o f

d i f f e r e n t

r o l e s /

a c t i v i t i e s

C r i t i c a l o r

h a z a r d o u s

w o r k ?

N

o . o f

w o r k

s c h

e d u l e s

T r a v e l a n d

d o m e s t i c

a r r a n g e m e n t s

T r a v e l

a c r o s s

m u l t i p l e

t i m e z o n e s

M u l t i p l e

g e o g r a p h i c a l

r e g i o n s

C o m m e n t s

S i t u a t i o n / d e c i s i o n r e q u i r e d

A d r i l l i n g s u p e r v i s o r n e e d s t o

d e c i d e

w h e t h e r t o a l l o w a w o r k e r

w h o h a s a l r e a d y w o r k e d a n

a d d i t i o

n a l 2 h o u r s o v e r t i m e a t t h e

e n d o f

a 1 2 - h o u r s h i f t t o c a r r y o n

w o r k i n

g o n a s a f e t y - c r i t i c a l t a s k

f o r a n o

t h e r 2 h o u r s .

A d r i v e r a b o u t t o s t a r t a j o u r n e y

n e e d s

t o a s s e s s t h e r i s k t h a t

h e / s h e

w i l l b e e x c e s s i v e l y

f a t i g u e d b e f o r e r e a c h i n g t h e

i n t e n d

e d d e s t i n a t i o n .

T h e m a n a g e r o f a s m a l l t e r m i n a l

w i t h a

w o r k f o r c e , c o m p r i s i n g f i e l d

o p e r a t

o r s , t e c h n i c i a n s , s e c u r i t y

p e r s o n

n e l a n d c o n t r o l r o o m

o p e r a t

o r s , w a n t s t o d e m o n s t r a t e

t h a t t h

e r i s k o f o p e r a t o r f a t i g u e i n

t e r m s o f i t s p o t e n t i a l f o r m a j o r

a c c i d e n t s i s b e i n g m a n a g e d t o

l e v e l s w h i c h a r e a s l o w a s

r e a s o n

a b l y p r a c t i c a b l e ( A L A R P ) .

T h e o f f s h o r e i n s t a l l a t i o n m a n a g e r

o f a l a r g e p r o d u c t i o n p l a t f o r m

w a n t s

t o d e m o n s t r a t e t h a t t h e

r i s k o f

o p e r a t o r f a t i g u e i n t e r m s o f

t h e p o

t e n t i a l f o r m a j o r a c c i d e n t s

i s b e i n

g m a n a g e d i n a c c o r d a n c e

w i t h t h

e A L A R P p r i n c i p l e .

1 1 2 0

2 0 0

n e x t 2

h o u r s

n e x t 8

h o u r s

l o n g -

t e r m

l o n g -

t e r m

1 1 3 o r 4

m a n y

y e s

y e s

y e s

y e s

1 1 2 1

n / a

s i n g l e

W o r k f o r c e a l l

l i v e a t h o m e

a n d t r a v e l f o r

l e s s t h a n 1 h o u r

t o w o r k d a i l y .

A l l t h e

w o r k f o r c e l i v e

a n d w o r k o n

t h e p l a t f o r m .

n o

n o

n o

S o m e k e y

p e r s o n n e l

t r a v e l l o n g

d i s t a n c e s t o

g e t t o t h e

p l a t f o r m .

n / a n

o n o

n o

A s s e s s m e n t c a n b e m a

d e u s i n g

t h e P r i o r S l e e p C a l c u l a t o r .

A s s e s s m e n t c a n b e m a

d e u s i n g

t h e P r i o r S l e e p C a l c u l a t o r .

A n a l y s i s n e e d s t o c o n s i d e r b o t h

w o r k s c h e d u l e s s e p a r a t e l y —

i . e . t o t r e a t e a c h a s a s e

p a r a t e

a s s e s s m e n t u n i t .

A n a l y s i s c a n b e c o n d u c t e d u s i n g

a b i o m a t h e m a t i c a l m o d e l .

A n a l y s i s c a n b e c o n d u c t e d u s i n g

a b i o m a t h e m a t i c a l m o d e l .

R o l e s s h o u l d b e g r o u p e d i n t o

a s s e s s m e n t u n i t s a c c o r d i n g t o

c r i t i c a l i t y a n d i n h e r e n t

t a s k

s e n s i t i v i t y o f t h e w o r k i n v o l v e d ,

w i t h a p p r o p r i a t e f a t i g u

e

t o l e r a n c e l e v e l s .

c o n t i n u e d …


21/40

17


T a b l e 2 T h e d i f f e r e n t a p p r o a c h e s t o p e r f o r m i n g f a

t i g u e r i s k a s s e s s m e n t s i n d i f f e r e n t s i t u a t i o

n s ( c o n t i n u e d )

P o p u l a t i o n

t o b e

a s s e s s e d

T i m e

p e r i o d

N o . o f

d i f f e r e n t

r o l e s /

a c t i v i t i e s

C r i t i c a l o r

h a z a r d o u s

w o r k ?

N o . o f

w o r k

s c h e d u l e s

T r a v e l a n d

d o m e s t i c


T r a v e l

a c r o s s

m u l t i p l e

t i m e z o n e s

M u l t i p l e


r e g i o n s

C o m m e n t s


A n e x p

l o r a t i o n c o m p a n y c a r r y i n g

o u t e s s e n t i a l l y t h e s a m e

o p e r a t

i o n i n d i f f e r e n t l o c a t i o n s

a r o u n d t h e w o r l d w a n t s t o

p e r f o r m a s i n g l e f a t i g u e r i s k

a s s e s s m e n t t h a t c a n b e a p p l i e d t o

a l l f i e l d o p e r a t i o n s w o r l d w i d e .

A n o p e r a t i n g c o m p a n y c a r r y i n g

o u t a r

a n g e o f e x p l o r a t i o n a n d

p r o d u c t i o n o p e r a t i o n s i n d i f f e r e n t

l o c a t i o

n s a r o u n d t h e w o r l d w a n t s

t o p e r f o r m a s i n g l e f a t i g u e r i s k

a s s e s s m e n t t h a t c a n b e a p p l i e d t o

a l l o p e

r a t i o n s w o r l d w i d e .

1 , 0

0 0

m a n y

‘ 0 0 0 s

l o n g -

t e r m

l o n g -

t e r m

m a n y

m a n y

y e s

y e s

f e w

m a n y

A l l t h e

w o r k f o r c e l i v e

o n t h e p l a t f o r m

o r i n c a m p

w h i l e o n

r o t a t i o n .

v a r i e d

s o m e

y e s

y e s

y e s

O n e c o m p r e h e n s i v e a n

a l y s i s

s h o u l d b e a p p r o p r i a t e

f o r m o s t

o f t h e f i e l d w o r k f o r c e , a l t h o u g h

v a r i a n t s m a y n e e d t o b

e

a s s e s s e d w h e r e t h e r e a

r e

s i g n i f i c a n t d i f f e r e n c e s .

A

s e p a r a t e a n a l y s i s w i l l b

e n e e d e d

f o r t h o s e i n d i v i d u a l s w h o t r a v e l

a c r o s s t i m e z o n e s .

A s s u m p t i o n s a b o u t s l e

e p q u a l i t y

a n d c i r c a d i a n a d a p t a t i o n s h o u l d

b e c h e c k e d l o c a l l y i n d

i f f e r e n t

g e o g r a p h i c a l r e g i o n s .

R o l e s s h o u l d b e g r o u p e d

a c c o r d i n g t o c r i t i c a l i t y

a n d

i n h e r e n t t a s k s e n s i t i v i t y o f t h e

w o r k i n v o l v e d , w

i t h a p p r o p r i a t e

f a t i g u e t o l e r a n c e l e v e l s s e t f o r

d i f f e r e n t g r o u p s .

I t i s n o t p o s s i b l e t o c o n

d u c t a

s i n g l e F R A f o r t h e w h o l e

c o m p a n y . T h e b u s i n e s s s h o u l d

b e o r g a n i z e d i n t o a n u m b e r o f

a s s e s s m e n t u n i t s t h a t a r e s i m i l a r

i n t e r m s o f t h e k e y f a c t o r s a n d

i n d i v i d u a l a n a l y s e s p e r

f o r m e d

f o r e a c h .

G e n e r i c b u s i n e s s - w i d e

f a t i g u e

r i s k t o l e r a n c e l e v e l s s h o u l d b e

d e f i n e d , b a s e d o n r o l e

a n d

a c t i v i t y t y p e s , a n d a p p l i e d

c o n s i s t e n t l y a c r o s s t h e

d i f f e r e n t

o p e r a t i o n s .

c o n t i n u e d …


22/40

OGP • IPIECA

18

T a b l e 2 T h e d i f f e r e n t a p p r o a c h e s t o p e r f o r m i n g f a

t i g u e r i s k a s s e s s m e n t s i n d i f f e r e n t s i t u a t i o

n s ( c o n t i n u e d )

P o p u l a t i o n

t o b e

a s s e s s e d

T i m e

p e r i o d

N o . o f

d i f f e r e n t

r o l e s /

a c t i v i t i e s

C r i t i c a l o r

h a z a r d o u s

w o r k ?

N o . o f

w o r k

s c h e d u l e s

T r a v e l a n d

d o m e s t i c


T r a v e l

a c r o s s

m u l t i p l e

t i m e z o n e s

M u l t i p l e


r e g i o n s

C o m m e n t s


A s p e c

i a l i s t c o n t r a c t o r w h o

s u p p l i e s a r a p i d r e s p o n s e s e r v i c e

i n v o l v i n g f l y i n g t e c h n i c a l

s p e c i a l i s t s f r o m N o r t h e r n E u r o p e

t o w o r

l d w i d e l o c a t i o n s a t s h o r t

n o t i c e

i s c o n s i d e r i n g a c h a n g e t o

w o r k p

r a c t i c e s a n d w a n t s t o

a s s e s s

t h e r i s k t h a t t h e s p e c i a l i s t s

w i l l e x p e r i e n c e s i g n i f i c a n t l y m o r e

f a t i g u e a t t h e w o r k s i t e c o m p a r e d

w i t h c u r r e n t a r r a n g e m e n t s .

T h e m a n a g e r o f a r o a d t r a n s p o r t

o p e r a t i o n w a n t s t o a s s e s s t h e

f a t i g u e r i s k i f c h a n g e s a r e m a d e

t o t h e

s h i f t s c h e d u l e s f o r a s m a l l

t e a m o

f t a n k e r d r i v e r s w o r k i n g

f r o m t h e s a m e u r b a n l o c a t i o n ;

t h e p r o p o s e d c h a n g e s w o u l d

r e s u l t i n t h e d r i v e r s s t a r t i n g w o r k

2 h o u r

s

Documents

Assessing risks from operator fatigue